Prevent adjacent unary operators from merging (#328)

Summary: Pull Request resolved: #328

Reviewed By: strulovich

Differential Revision: D37003050

Pulled By: cgrushko

fbshipit-source-id: 010cd6a400d88aed8e253718658ec93464dd0b5f

Author: nreid260

core/src/main/java/com/facebook/ktfmt/format/KotlinInputAstVisitor.kt

@@ -111,7 +111,6 @@ import org.jetbrains.kotlin.psi.KtTypeParameter
 import org.jetbrains.kotlin.psi.KtTypeParameterList
 import org.jetbrains.kotlin.psi.KtTypeProjection
 import org.jetbrains.kotlin.psi.KtTypeReference
-import org.jetbrains.kotlin.psi.KtUnaryExpression
 import org.jetbrains.kotlin.psi.KtUserType
 import org.jetbrains.kotlin.psi.KtValueArgument
 import org.jetbrains.kotlin.psi.KtValueArgumentList
@@ -1137,19 +1136,33 @@ class KotlinInputAstVisitor(
     builder.close()
   }
 
-  override fun visitUnaryExpression(expression: KtUnaryExpression) {
+  override fun visitPostfixExpression(expression: KtPostfixExpression) {
     builder.sync(expression)
     builder.block(ZERO) {
-      visit(expression.baseExpression)
-      builder.token(expression.operationReference.text)
+      val baseExpression = expression.baseExpression
+      val operator = expression.operationReference.text
+
+      visit(baseExpression)
+      if (baseExpression is KtPostfixExpression &&
+          baseExpression.operationReference.text.last() == operator.first()) {
+        builder.space()
+      }
+      builder.token(operator)
     }
   }
 
   override fun visitPrefixExpression(expression: KtPrefixExpression) {
     builder.sync(expression)
     builder.block(ZERO) {
-      builder.token(expression.operationReference.text)
-      visit(expression.baseExpression)
+      val baseExpression = expression.baseExpression
+      val operator = expression.operationReference.text
+
+      builder.token(operator)
+      if (baseExpression is KtPrefixExpression &&
+          operator.last() == baseExpression.operationReference.text.first()) {
+        builder.space()
+      }
+      visit(baseExpression)
     }
   }
 

core/src/test/java/com/facebook/ktfmt/format/FormatterTest.kt

@@ -2904,7 +2904,7 @@ class FormatterTest {
       |""".trimMargin())
 
   @Test
-  fun `Unary expressions`() =
+  fun `Unary prefix expressions`() =
       assertFormatted(
           """
       |fun f() {
@@ -2914,6 +2914,39 @@ class FormatterTest {
       |  +4
       |  ++a
       |  --a
+      |
+      |  + +a
+      |  +-a
+      |  +!a
+      |  -+a
+      |  - -a
+      |  -!a
+      |  !+a
+      |  !a
+      |  ! !a
+      |
+      |  + ++a
+      |  +--a
+      |  -++a
+      |  - --a
+      |  !++a
+      |  !--a
+      |}
+      |""".trimMargin())
+
+  @Test
+  fun `Unary postfix expressions`() =
+      assertFormatted(
+          """
+      |fun f() {
+      |  a!!
+      |  a++
+      |  a--
+      |
+      |  a--!!
+      |  a++!!
+      |
+      |  a!! !!
       |}
       |""".trimMargin())